Renal Sympathetic Denervation and Daily Life Blood Pressure in Resistant Hypertension: Simplicity or Complexity?
Drug resistant hypertension is a clinically relevant problem, which has attracted increasing attention over the past few years. This is certainly due to a growing awareness of the importance of blood pressure (BP) control in reducing hypertension-related cardiovascular risk. It is also due, however, to a recent major technological breakthrough in the management of resistant hypertension, because of the introduction of two novel invasive therapeutic approaches: carotid baroreceptor stimulation and catheter based renal sympathetic denervation (RDN) 1, 2. For a number of reasons the latter method seems to be taking the upper hand, and is used with growing enthusiasm all over the world, even if the strength of the evidence in its support is not currently overwhelming.
The concept of RDN derives from a known pressor effect of sympathetic stimuli, arriving to the kidney via efferent fibers located in the adventitia of renal arteries, in the frame of a complex regulation of sympathetic activity also including reflex modulation by renal afferent neural influences 3, 4, 5. Hence the hypothesis was made that destruction of these fibers, by bilaterally applying radiofrequency electrical current through an ablation catheter positioned inside renal artery, might reduce sympathetic activity in general. It was also hypothesized that, in particular, renal sympathetic fibers ablation might interfere with sympathetic renal modulation, leading to increased sodium and water excretion and to vasodilation, thereby effectively lowering elevated BP levels. This hypothesis has been first tested in animal studies 3, 4, 5and, subsequently explored in two major studies in humans: Symplicity HTN-1 6 and Symplicity HTN-27 followed by a growing number of reports from registries.
- Received June 13, 2013.
- Accepted June 14, 2013.